This invention relates to a device for cutting fibrous material into shorter lengths for use in the textile industry and more particularly the invention relates to an outside-in tow cutter.
Modern devices for cutting fibrous material, tow, in the textile industry are, in general, improvements on the basic type tow cutter as patented by Garland Keith in U.S. Pat. No. 3,485,120 in 1069. Such apparatus are designed so that a number of layers of uncut tow are wrapped spirally on the radially outturned cutting edges of a plurality of blades whose edges are uniformly spaced from the center of rotation of the reel upon which the blades are mounted. Such reels are constructed of a disc with a center mounted hub for powered rotation, and a ring that supports one end of the cutting blades. The disc and ring thus form flanges between which the tow wound on the reel is held. A cylindrical pressure roller fits snugly between the flanges and its periphery is held at a uniform distance from the cutting edges of the blades, thereby forcing the tow radially inward to the cutting blades. Such machines were initially used for process speeds up to as high as 500 meters per minute; however, with the development of higher speed spin-draw lines in the man-made fiber industry, speeds have increased substantially above 500 meters per minute and centrifugal force has become a major factor in the function of the Garland Keith concept. With higher rotational speeds the mass of uncut tow plus the mass of cut staple inside the cutting edges of the blades becomes a substantial factor.
It is therefore an object of this invention to provide a tow cutter capable of operating at speeds in excess of 2,000 meters per minute.
It is another object of the instant invention to reduce the mass of cut fibrous material carried by the reel during operation thereby reducing the centrifugal forces and consequent stress placed on the uncut tow.
Yet another object of the invention is to provide a more gradual cutting action between the pressure roller and the cutting blades thereby reducing the impact forces of high speed operation.
Still another object of the invention is to provide a tow cutter which is self-threading at initial start-up and can be threaded with a second tow while a first tow is running on the reel.